Field of the Invention
The present invention relates to an inspection probe and an IC socket with the same.
Description of the Related Art
On a semiconductor device serving as an electronic device to be mounted on electronic equipment or the like, a test for eliminating a potential failure is generally performed by use of a semiconductor device socket at a stage before the device is mounted. The semiconductor device socket used for the test or the mounting is generally referred to as an IC socket (integrated circuit socket), which is disposed on a printed wiring board (a test board or a mounting board) as disclosed in Japanese Patent Laid-Open No. 2010-157386, for example. In the IC socket, a plurality of inspection probes (which are referred to as contacts in Japanese Patent Laid-Open No. 2010-157386) for electrically connecting the above-mentioned semiconductor device to the printed wiring board are provided in a base member.
As shown in FIG. 1 in Japanese Patent Laid-Open No. 2010-157386, for example, an inspection probe comprises: a plunger provided with multiple plate-like contact pieces which come into contact with an electrode of a semiconductor device; and a coil spring unit configured to bias the plunger. The plunger is formed by pressing a thin sheet made of a copper alloy. Moreover, the coil spring unit is formed from a stainless steel wire or a piano wire, and comprises: a spring portion into which a lower part of the plunger is inserted; and a wound tight portion which is continuous with the spring portion.
A reduction in a resistance value of the coils spring unit is essential to the above-described inspection probe in order for transmitting an electric signal from the plunger via the coil spring unit. Thus, in a quest to reduce the resistance value, the wound tight portion of the coil spring unit is brought into close contact. Alternatively, as a surface treatment of the coils spring unit, thickening plating is performed on the coil spring unit by using a material having a relatively low resistance value such as gold (Au), copper (Cu), and silver (Ag).
Moreover, as shown in FIG. 10 in Japanese Patent Laid-Open No. 2006-266869, there is also proposed an inspection probe in which upper and lower contact portions, a spring portion, and a short-circuit piece are integrally formed in order to reduce the number of components and to secure large expansion and contraction amounts. The short-circuit piece is configured such that its lower end portion does not come into contact with the lower contact portion when the spring portion is not compressed and such that the lower end portion comes into contact with the lower contact portion when the spring portion is compressed. Herewith, conduction is established between the upper contact portion and the lower contact portion through the short-circuit piece.